Re: parsing a numeric field (timings)

[bmorris@xxxxxxxxxx]

>Date: Sun, 22 Apr 2001 07:33:10 -0700
>From: "James W. Kilgore" <qappdsn@attglobal.net>
>
>There is a production program that gets run each night on this machine
against
>about 200,000 records that does a lot of Z-ADD's and takes about 25
minutes to
>complete.  Just out of curiosity, since this is on a CISC box, I'm going
to
>replace some of the Z-ADD's with MOVE's and see what difference it makes.
I'll
>report the results.

Be very careful when replacing Z-ADD with MOVE.

James, this isn't particularly directed at you (especially
since you've established that the difference is insignificant)
but rather at anyone reading this thread and thinking of
setting up a new rule saying never to use Z-ADD.  Consider
these fields:

NUM1 packed(5,2) value 123.45 dim(5)
NUM2 packed(3,1) value 67.8

Starting with the NUM1 elements all having the same initial value,
what values do the NUM1 elements have after each operation?  What
if NUM2 were -678.9?

1. Z-ADD     NUM2    NUM1(1)
2. MOVE      NUM2    NUM1(2)
3. MOVE(P)   NUM2    NUM1(3)
4. MOVEL     NUM2    NUM1(4)
5. MOVEL(P)  NUM2    NUM1(5)

If you don't know the answers immediately (without having to look
in the manual to verify them) for at least the first three, then
you should stay away from MOVE even if it's a bit faster.  Even if
you do know the answer you should stay away from MOVE for numerics.
It's just too bizarre.

Hint: all 5 answers are different.

Barbara Morris


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